The present invention relates in general to combination locks of the tumbler wheel type, and more particularly to the tumbler wheel type combination locks having a scrambler or tumbler upsetting mechanism for displacing the angular positions of one or more of the tumbler wheels during retraction of the lock bolt to unlocked position place the tumbler wheel gates so that they will no longer be disposed in fence-receiving, unlocking alignment when the bolt is returned to projected or locking position.
Conventional combination locks as usually manufactured comprise three or four tumbler wheels which are loosely journalled in a coaxial, side-by-side, spaced stack relationship for rotation within a lock casing on a hollow tubular tumbler post projecting inwardly from the front wall of the tumbler casing. The lock dial, which usually has one hundred peripheral calibration marks thereon, is affixed to a dial spindle which extends through the hollow center of the tumbler post and has keyed to the inner end thereof a drive cam which is likewise arranged coaxially with and spaced rearwardly from the stack of tumbler wheels. Each of the tumbler wheels is provided with a peripheral notch or gate at a selected radial position to receive a fence bar projecting from a fence lever when properly oriented, and the drive cam is similarly provided with a peripheral gate for receiving a nose formation projecting from an end of the fence lever.
A drive pin projects forwardly from the drive cam to provide a lost motion coupling with a conventional fly rotated through a limited arc and associated with the rearmost tumbler wheel to drive the rearmost tumbler wheel in selected relation to the drive cam. A similar lost motion coupling is provided between each of the successive tumbler wheels so that each of the tumbler wheels may be driven upon predetermined rotation of the drive cam. A thin spacer washer is also customarily provided between each of the tumbler wheels, in association with a fly member which typically comprises a ring portion journalled in concentric relation with the associated tumbler wheel and a radial projection which lies between a pair of stop shoulders on the associated tumbler wheel to limit angular rotation of the fly to about 20 degrees. A drive pin or lug projects from the adjacent tumbler wheel into position to abut the radial projection of the fly member and transmit rotation to the adjacent tumbler wheel after the fly member has moved through its predetermined lost motion angular range.
A fence lever is pivotally connected near one end of a reciprocative bolt slidably supported in the lock casing. The fence lever typically has a depending nose formation near the free end of the fence lever to ride upon the drive cam periphery, and the fence lever additionally usually includes a bar or fence projecting laterally from the fence lever in overlying relation to the peripheries of the tumbler wheels. The position of the fence in relation to the length of the fence lever nose is usually such that the fence is spaced outwardly from the peripheries of the tumbler wheels when the fence lever nose rides on the drive cam periphery. Such combination locks are opened by rotation of the dial in a predetermined sequence clockwise and counterclockwise through predetermined numbers of revolutions to numerical positions forming an opening combination, which effects angular rotation of the tumbler wheels to positions resulting in alignment of their peripheral gates with the fence, so that when the dial is then rotated to bring the drive cam gate to a position registered with the fence lever nose, the fence lever nose and fence drop into the gates so that further rotation of the dial through a partial revolution achieves retraction of the bolt. To improve security of the lock against unauthorized entry, it is desirable in many instance to provide some sort of tumbler upsetting mechanism or tumbler scrambling assembly such that, when the bolt is being retracted, one or more of the tumbler wheels is engaged and moved to an upset or changed angular position. Preferably, the tumbler upsetting or scrambler mechanism should be of such a nature as not to necessitate any enlargement of the lock housing or change the relation of the tumblers and the bolt and fence lever from the normal construction of these components.
Heretofore, a number of such tumbler upsetting or scrambler mechanisms have been proposed, for example as shown in the Eiffert et al U.S. Pat. No. 2,625,032, the Miller et al U.S. Pat. No. 3,339,382 and the Miller et al U.S. Pat. No. 3,533,253, all owned by the Assignee of the present application. Such tumbler upsetting or scrambler mechanisms as shown in these prior patents, however, involve modification of some part of the lock mechanism which is moved to affect bolt retraction and projection between locking and unlocking position or special configuration of the interior mechanism chamber of the lock casing so as to accept the tumbler upsetting or scrambler assembly and the bolt or bolt plate in such locks is not spring-biased to the projected or locking position.
An object of the present invention is the provision of a novel tumbler scrambler assembly which is provided as a self-contained assembly insertable in a tumbler wheel type combination lock without significant modification of the usual lock components, and which may be simply assembled onto a pivot post provided in the lock housing.
Another object of the present invention is the provision of a novel tumbler scrambler mechanism for upsetting the angular positions of tumbler wheels of a tumbler wheel type combination lock during retraction of the locking bolt to the withdrawn or unlocking position when the fence leaves the tumbler gates near the end of the bolt-retracting stroke, wherein the tumbler scrambler mechanism is incorporated into mating housing halves which can be readily assembled together and mounted on a supporting post protruding rearwardly from the front wall of the lock casing, and wherein the mating scrambler housing halves have U-shaped mounting ears forming oppositely directed, interfitting protrusions to embrace and assemble the scrambler mechanism onto the mounting post.
Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention.